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brake antilock computer location
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Rick Dempsey
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Apr 23, 2009, 7:37 AM
Post #1 of 19
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brake antilock computer location
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1992 Ford F150. Can anyone tell me where the rear brake antilock computer is located. My friend was driving his F150 on an express highway and the rear brakes locked up almost flipping the truck. He brought the truck in for brake service and they bypassed the antilock module valve. I'v since diconnected it electrically because the valve had shorted. Now I would like to finish the job and disconnect the computer. Once this is accomplished I hope the light will turn off. If not I'll remove the lamp as well. Thanking you in advance
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flgmtech1
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Apr 23, 2009, 1:48 PM
Post #2 of 19
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Re: brake antilock computer location
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The Rear Antilock Brake (RABS) control module is located behind the right side of the instrument panel.
This sounds scary! I have never heard of an ABS Module locking up brakes, I know of no GM that has had that occur, or there would be serious recalls, can you tell me the cause of the rear brake lock up?
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way2old
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Apr 23, 2009, 2:52 PM
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Re: brake antilock computer location
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I see you figured out how to post pictures in the reply. 
Being way2old is why I need help from younger minds
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Rick Dempsey
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Apr 24, 2009, 4:00 PM
Post #4 of 19
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Re: brake antilock computer location
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I'm not sure as the truck was in a metropolitan area at the time. All I know is what I was told. The rear brakes lock up at highway speed. My friend took the truck in to have the brakes checked out. He was told there was no problem with the rear brakes. After the lock up the anti lock light stays on so I was asked to look at it. I see the valve was hydraulically bypassed. I know it wasn't before he left. I'm just going to elimate the system altogether to turn off the light. I have had GM trucks with rear anti lock brakes and never encountered any problems whatsoever. He hasn't had a problem with the rear brakes since then. I know for a fact the rear brakes on his truck were brand new,not cheap,and the fluid system flushed. I've seen shoes delaminate rotate around and get stuck and jam the opposite shoe thereby locking the brake. This didn't happen in this case. Sorry I don't have anymore details and I thank you for the information.
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Loren Champlain Sr
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Apr 24, 2009, 4:04 PM
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Re: brake antilock computer location
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Rick; I was thinking about this today. Is it possible that a tooth broke off the ring gear and locked up the rear end? I've seen it happen on more than one GM. Since the reluctor wheel is attached to the carrier, could cause an ABS light, as well. Might want to pull the differential cover and take a look?
Loren
SW Washington
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Rick Dempsey
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Apr 24, 2009, 4:33 PM
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Re: brake antilock computer location
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Thank you very much. This is a 1992 Ford F150 and I will check it out. That makes alot of sense. He has never had the rear end checked out. He is away for the weekend and will be returning sunday. I'm happy he didn't take the truck. I'll explain what I have learned to him. This event really scared the @#%& out of him. I'm sure I'll get the green light to proceed. Thanks again, your time and effort is greatly appreciated. I'll follow up with anything I find.
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Loren Champlain Sr
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Apr 24, 2009, 4:41 PM
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Re: brake antilock computer location
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OOooppps. F150? Yeah, that's a Ford. Should have paid more attention. Not a common problem with Fords. But, suppose it's worth a look, anyway.
Loren
SW Washington
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Hammer Time
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Apr 24, 2009, 4:46 PM
Post #8 of 19
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Re: brake antilock computer location
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I agree, I see no way for the ABS system to cause the lockup. The broken tooth suggestion is a possibility but I would think it would have to be a spider gear rather than the ring gear because you would feel that under acceleration with a damaged ring gear.
Could also be a bad master cylinder just locking up the brakes on it after time. Sounds like you need a closer examination and determine where the lockup actually occurred.
Unplugging the module likely won't turn the light off and likely won't be the source your real problem.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Apr 24, 2009, 4:52 PM)
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Rick Dempsey
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Apr 24, 2009, 4:48 PM
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Re: brake antilock computer location
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He could have easily mistaken a rear end lock up for a brake lock up. The inspection is a sure fire way to know. If the rear end is at fault then he may want the antilock working again. Right now he doesn't want anything to do with antilock brakes.
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Rick Dempsey
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Apr 24, 2009, 5:06 PM
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Re: brake antilock computer location
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I understand the antilock light functions as a "system inop". To turn off the light the system must be operational. If I disconnect the computer there is no system therefore no light. Correct me,please, if I am incorrect.
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Hammer Time
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Apr 24, 2009, 5:11 PM
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Re: brake antilock computer location
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The light is designed to find faults in the system. The module being unplugged is a fault that I believe the system will recognize. I tried to do that on a Ford once before and the light stayed illuminated. The light defaults to "on" and a good system check is required to put it out.
I could be wrong but that was my experience on a different vehicle.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Jeff Norfolk
Enthusiast
Apr 24, 2009, 5:14 PM
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Re: brake antilock computer location
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That works on some of the older model stuff. Like older Chevys but not sure on the newer stuff. Some newer cars will flag a light though the ECM if it has no communication from the BCM. Unplug it and give it a try. Won't hurt a thing to try.
Jeff
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Rick Dempsey
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Apr 24, 2009, 5:19 PM
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Re: brake antilock computer location
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Same is the case here the light is on and with the module disconnected the light stays on. The modlue is in fact defective in this case. Until I can prove otherwise he strongly believes the antilock system is the root of his problem. I will need physical evidence to change his mind. I'm up for the challenge.
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Hammer Time
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Apr 24, 2009, 5:22 PM
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Re: brake antilock computer location
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ABS systems are engineered to release brakes, not apply them so it's pretty hard for an ABS system to apply brake pressure on it's own. I think you are looking for a different cause that just happens to effect the ABS also.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Rick Dempsey
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Apr 24, 2009, 5:29 PM
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Re: brake antilock computer location
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Other than a defective module, the brake system works flawlessly. Sometimes, I need to go backwards to go forewards. I'll start at the rear end and go foreward from there.
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Hammer Time
Ultimate Carjunky
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Apr 24, 2009, 5:33 PM
Post #17 of 19
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Re: brake antilock computer location
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Your first step is to determine exactly what stopped the car, whether it was the brake shoes or something else that got jammed somewhere. Look for overheated drums or marks in a housing somewhere but you have to start with the actually point that took the brunt of force.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Rick Dempsey
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Apr 24, 2009, 5:47 PM
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Re: brake antilock computer location
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I totally agree. I let you how this all pans out.
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rickdempsey415@hotmail.com
Jun 16, 2009, 2:59 PM
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Re: brake antilock computer location
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I know there has been some time pass since I last posted. All is well now with the antilock system. I got it working again by removing cleaning and reinstalling all the connectors in the system. The story changed afew times by the owner of the truck. So I really do not know exactly what happened to him. There are no broken parts in the rear end either. This person is a carpenter and any discussions of a mechanical nature are akin to Chinese to him. I went over the front and rear brake systems and found nothing unusual or abnormal. He's driving the truck and all is well. Thank you all for your input.
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